Connector for a respiratory mask and a respiratory mask

ABSTRACT

A respiratory mask assembly for delivering breathable gas to a patient includes a frame and an elbow assembly. The frame has a front surface and a rear surface adapted in use to face the patient. The frame includes a main body providing an aperture therethrough for the introduction of breathable gas into a nasal breathing cavity. The elbow assembly is swivelably coupled to the front surface of the frame. The elbow assembly includes a swivel elbow that defines an intake port and an exhaust port separated from the intake port using a baffle. The elbow assembly includes an end portion that interfaces with the aperture of the frame.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a connector for a respiratory mask anda respiratory mask.

The invention has been developed primarily for use with a breathable gassupply apparatus in Continuous Positive Airway Pressure (CPAP) treatmentof, for example, Obstructive Sleep Apnea (OSA) and other ventilatoryassistance treatments, such as Non Invasive Positive PressureVentilation (NIPPV) and will be described hereinafter with reference tothese applications. However, it will be appreciated that the inventionis not limited to these particular fields of use and also findsapplication in, for example, assisted respiration, mechanicalventilation and the like.

2. General Background and Related Art

CPAP treatment is a common ameliorative treatment for breathingdisorders including OSA. CPAP treatment, as described in U.S. Pat. No.4,944,310, provides pressurized air or other breathable gas to theentrance of a patient's airways at a pressure elevated above atmosphericpressure, typically in the range 3-20 cm H₂O.

It is also known for the level of treatment pressure to vary during aperiod of treatment in accordance with patient need, that form of CPAPbeing known as automatically adjusting nasal CPAP treatment, asdescribed in U.S. Pat. No. 5,245,995.

NIPPV is another form of treatment for breathing disorders which caninvolve a relatively higher pressure of gas being provided in thepatient mask during the inspiratory phase of respiration and arelatively lower pressure or atmospheric pressure being provided in thepatient mask during the expiratory phase of respiration.

In other NIPPV modes, the pressure can be made to vary in a complexmanner throughout the respiratory cycle. For example, the pressure atthe mask during inspiration or expiration can be varied through theperiod of treatment, as disclosed in the applicant's international PCTpatent application No. PCT/AU97/00631.

Typically, the ventilatory assistance for CPAP or NIPPV treatment isdelivered to the patient by way of a respiratory, preferably nasal,mask. Alternatively, a mouth mask or full face mask can be used. In thisspecification any reference to a mask is to be understood asincorporating a reference to a nasal mask, mouth mask or full face mask,unless otherwise specifically indicated.

In this specification any reference to CPAP treatment is to beunderstood as embracing all of the above-described forms of ventilatorytreatment or assistance.

Breathable gas supply apparatus broadly comprise a flow generatorconstituted by a continuous source of air or other breathable gasgenerally in the form of a blower driven by an electric motor. Theelectric motor driving the blower is typically controlled by aservo-controller under the control of a micro controller unit. Ahospital piped supply can also be used. The gas supply is connected to aconduit or tube which, in turn, is connected to the patient's mask whichincorporates, or has in close proximity, a gas washout vent for ventingexhaled gases to the atmosphere. The gas washout vent is sometimesreferred to as a CO₂ washout vent.

As CPAP and NIPPV treatments are normally administered while the patientis sleeping, minimization of the noise is desirable for both the comfortof the patient and any bed partner. The exhausting of exhaled gas to theatmosphere through the gas washout vent creates noise due to turbulencegenerated at a shear layer between the moving vented gases and the stillatmospheric air.

It is also desirable to locate the vent as close as possible to the maskin a location which encourages a circulation of flow within the mask soas to eliminate exhaled CO₂ through the vent and encourage inhalation ofthe supplied breathable gas. In this way, the retention of CO₂ withinthe mask is minimized. Further, by increasing the venting efficiency inthis manner, the overall gas outflow is minimized, thereby reducing theopportunity for noise production.

One approach to minimize the noise generated by the venting of theexhaled gas is to direct the gas along an exterior surface which is asmooth prolongation of an interior surface of the outlet of the gaswashout vent. This reduces the interaction between the vented gas andthe still atmospheric air and, thus, the noise generated.

An example of the above approach is the AeroClick vent produced by MAPwhich has an annular vent passage that directs the exhaled gases alongan adjacent cylindrical section of equal exterior diameter to theinterior diameter of the annular vent. The AeroClick vent suffers fromseveral disadvantages. Firstly, the annular vent is incorporated into aswivel mechanism which requires a certain amount of play or clearance inorder to rotate freely. This play allows the components forming theinterior and exterior surfaces of the annular vent passage to becomemisaligned and the size of the vent outlet being decreased from optimumin some regions and increased from optimum in other regions. Thedecreased area regions increase by the velocity of the gas flowingtherethrough which increases noise and can produce an unpleasantwhistling effect. Secondly, the flow of the gas from the vent outlet toa state where its velocity is in substantial equilibrium with theatmosphere is interrupted by an external shoulder closely downstream ofthe vent outlet. The shoulder is provided to locate the gas supplyconduit. The stresses in the flow caused by the shoulder lead to thegeneration of noise. Additionally, the flow path from the gas conduitinto the vent outlet is not smooth which introduces discontinuities intothe flow which result in further noise generation.

Further, the AeroClick vent and other prior art devices that are of asubstantially cylindrical in-line configuration, the exhaled gas mustthus be forced a relatively large distance (typically around 60 mm)before reaching the outlet to the atmosphere. This reduces CO₂ washoutefficiency, as noted above, and requires additional patient effort toforce the gas against the direction of flow coming from the flowgenerator.

It is an object of the present invention to substantially overcome or atleast ameliorate the prior art disadvantages and, in particular, toreduce the noise generated by venting exhaled gases to the atmosphere.

SUMMARY OF THE INVENTION

Accordingly, in a first aspect, the present invention provides aconnector comprising:

a mask end for connecting in fluid communication with the interior of arespiratory mask;

a supply conduit end disposed at an angle to the mask end for connectingin fluid communication with the outlet of a breathable gas supplyconduit; and

a gas washout vent passage having an inlet adjacent to, or forming partof, the mask end in fluid communication with the interior of therespiratory mask and an outlet in fluid communication with theatmosphere, the outlet including an interior surface that forms a smoothprolongation with an adjacent exterior surface of the connector, thevent outlet is disposed on the side of the connector remote the maskend, has a generally part-annular cross section and is adapted to directthe washout gas in a direction substantially perpendicular to thelongitudinal axis of the mask end and substantially parallel to thelongitudinal axis of the supply conduit end towards the supply conduitend.

The supply conduit end is preferably substantially perpendicular to themask end. The supply conduit end can also be angled at approximately 135degrees to the mask end.

Preferably, the connector includes a body portion and a cap portion,said body portion including said interior surface. The cap portionpreferably also includes an interior surface spaced apart from the bodyportion interior surface, said body portion interior surface and saidcap portion interior surface defining said vent passage therebetween.

The cap portion is desirably detachable from the body portion. The capportion and body portion are also desirably rigid and fixed relative toeach other when attached. The exterior of the body portion preferablyincludes grooves or ridges adapted to engage ridges or groovesrespectively on the interior of the cap portion to attach the capportion to the body portion. One of the body portion or cap portionpreferably also includes a spacer extending between said cap portioninterior surface and said body portion exterior surface.

In one form, the vent passage inlet is formed in the body portionadjacent to and downstream of the mask end, relative to the washout gasflow, and is in fluid communication with the mask interior via the bodyportion.

In another form, the vent passage inlet comprises part of the mask endand is in direct fluid communication with the mask interior.

The vent passage preferably comprises an inlet portion of relativelylarge cross-sectional area adjacent the vent passage inlet and an outletportion of relatively small cross-sectional area adjacent the ventpassage outlet.

The vent passage desirably comprises an inlet portion of constantcross-section, a relatively long outlet portion of constantcross-section and a relatively short transition portion of smoothlyreducing cross-section extending from the inlet portion to the outletportion. This shape reduces turbulence and affords a pressure drop fromthe interior of the mask to the outlet of the vent passage which reducesthe pressure gradient at the outlet of the vent passage and, thus,reduces the noise generated.

The vent passage can also include internal ribs and/or an internaltortuous path to increase the pressure drop, if required.

The body portion is preferably of generally part toroidal shape. The capportion is preferably of complimentary shape to a portion of theexterior of the body portion.

The vent passage preferably curves around the exterior of the bodyportion.

The connector desirably includes a swivel joiner at its supply conduitend, the exterior of the swivel joiner forming all, or a part, of saidconnector exterior surface.

In one form, the supply conduit end of the connector forms a smoothprolongation with the supply conduit. The supply conduit end and thesupply conduit desirably have a substantially equal external diameter.

In another form, the swivel joiner forms a smooth prolongation with thesupply conduit. The swivel joiner and the supply conduit having asubstantially equal external diameter. The swivel joiner preferablyincludes an end of reduced external diameter adapted to be receivedwithin the interior of the supply conduit.

In a second aspect, the present invention provides a respiratory maskcomprising:

a mask shell defining an interior of the respiratory mask;

a mask inlet for connecting in fluid communication with the outlet of abreathable gas supply conduit; and

a gas washout vent passage having an inlet forming part of the maskshell and in fluid communication with the interior of the respiratorymask and an outlet in fluid communication with the atmosphere, theoutlet including an interior surface that forms a smooth prolongationwith an adjacent exterior surface of the mask shell, the vent outlet isdisposed on the side of the mask remote the mask interior and is adaptedto direct the washout gas in a direction substantially parallel to thelongitudinal axis of the mask inlet and away from the mask inlet.

Preferably, the mask shell includes a body portion and a cap portion,said body portion including said interior surface. The cap portionpreferably also includes an interior surface spaced apart from the bodyportion interior surface, said body portion interior surface and saidcap portion interior surface defining said vent passage therebetween.

The cap portion is desirably detachable from the body portion. The capportion and body portion are also desirably rigid and fixed relative toeach other when attached. The exterior of the body portion preferablyincludes grooves or ridges adapted to engage ridges or groovesrespectively on the interior of the cap portion to attach the capportion to the body portion. One of the body portion or cap portionpreferably also includes a spacer extending between the interior surfaceof the cap portion and the exterior surface of the body portion.

The vent passage preferably comprises an inlet portion of a relativelylarge cross-sectional area adjacent the vent passage inlet and an outletportion of a relatively small cross-sectional area adjacent the ventpassage outlet.

The vent passage desirably comprises a relatively long inlet portion ofconstant cross-section, a relatively long outlet portion of constantcross-section and a transition portion of smoothly reducingcross-section extending from the inlet portion to the outlet portion.

The vent passage preferably substantially follows the shape of theexterior of the body portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a first embodiment of a connector in accordancewith the first aspect of the invention, shown attached to a nasalrespiratory mask and forehead support;

FIG. 2 is a cross-sectional side view of the connector shown in FIG. 1;

FIG. 3 is a perspective view of the connector shown in FIG. 1;

FIG. 4 is a perspective view of the connector shown in FIG. 1 with thecap portion removed;

FIG. 5 is an underside perspective view of the cap portion of theconnector shown in FIG. 1;

FIG. 6 is a cross-sectional side view of a second embodiment of aconnector in accordance with the first aspect of the invention;

FIG. 7 is a cross-sectional side view of a third embodiment of theconnector in accordance with the first aspect of the invention;

FIG. 8 is a cross-sectional side view of a first embodiment of arespiratory mask in accordance with the second aspect of the invention;and

FIG. 9 is a cross-sectional side view of a fourth embodiment of theconnector in accordance with the first aspect of the invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 show a first embodiment of the first aspect of theinvention in the form of connector 10. The connector 10 is shownattached to a nasal respiratory mask 12 and forehead support device 14.The connector 10 is also suitable for use with a full face (i.e., noseand mouth) respiratory mask.

The mask 12 comprises a substantially rigid mask shell 15, a flexiblemask cushion 16 and two slotted lower head strap connectors 18 (only oneconnector shown).

The forehead support device 14 includes a lower portion 20 which ispivotally mounted to an upper portion 22. The upper portion 22 includesforehead cushions 24 and two slotted upper head strap connectors 26(only one cushion/connector shown).

As best shown in FIG. 2, the connector 10 includes a mask end 28 forconnecting in fluid communication with the interior of the respiratorymask 12 and a supply conduit end 30 disposed substantiallyperpendicularly to the mask end 28 for connecting in fluid communicationwith the outlet of a breathable gas supply conduit 31. The mask end 28is rotatably coupled to the mask shell 15 by a retaining ring 29. Theclose proximity of the inlet ports 41, and the vent passage 32 overall,to the interior of the mask 12 advantageously increases CO₂ washoutefficiency.

The connector 10 also includes a gas washout vent passage, indicatedgenerally by the reference numeral 32, a body portion 34, a detachablecap portion 36 and a detachable swivel joiner 38. The conduit 31 is anon-rotatable friction push fit over end 38 a of the swivel joiner 38.The end 38 b of the swivel joiner 38 is a rotatable snap-engage fit withreduced diameter portion 39 of the body portion 34. The portion 39 isformed from resilient fingers to allow flexing during snap-engagementwith the swivel joiner 38.

The vent passage 32 includes a pair of inlet ports 41 (see FIG. 4)formed in the body portion 34 of the connector 10 adjacent the mask end28. The inlet ports 41 are in fluid communication with the interior ofthe mask 12 via the mask end 28. The vent passage 32 also includes anoutlet 40 opening to the atmosphere. The outlet 40 includes an interiorsurface 42 (comprising an exterior surface of the body portion 34) thatforms a smooth prolongation with an adjacent exterior surface 44 of thebody portion 34. The smooth prolongation between the interior surface 42and exterior surface 44 reduces noise by allowing the exhaled gases tovent along a continuous surface, as previously described. In order tominimize interruptions or disturbances that could generate turbulencedownstream of the outlet 40, and thus noise, the adjacent exteriorsurfaces 46, 48 of the swivel joiner 38 and the gas supply conduit 31respectively are also formed as smooth prolongations of the interiorsurface 42 and adjacent exterior surface 44.

As best shown in FIG. 3, the vent passage outlet 40 is of generally partannular cross-section subtending an angle of approximately 180° and islocated on the side of the connector 10 remote the mask end 28 and,thus, the mask 12. This ensures that gas is only vented along surfacesdisplaced, and facing away, from the mask 12 and the patient, whichagain minimizes the risk of the vented gases encounteringnoise-producing obstructions.

Returning to FIG. 2, it can be seen that the vent passage 32 comprisesan inlet portion 50 of relatively large cross-sectional area compared toan outlet portion 52 of relatively small cross-sectional area. Thisprovides a substantial pressure drop across the vent passage 32 andreduces the pressure drop between the outlet 40 and surroundingatmospheric air, again minimizing noise production. Also, the outletportion 52 is relatively long in order to allow the gas to approach alaminar state and, thus, minimize turbulence before the gas exits to theatmosphere. A smooth tapering transition portion 54 is disposed betweenthe inlet portion 50 and the outlet portion 52 which minimizes noiseproduction by minimizing the introduction of any discontinuities intothe gas flow.

As best shown in FIGS. 3 and 4, the body portion 34 includes grooves 56which are adapted to engage with ridges 58 provided on the cap portion36 to allow the cap portion 36 to be manually attachable/detachableto/from the body portion 34 for ease of cleaning and replacement. Asbest shown in FIG. 5, the cap portion 36 also includes an interiorstrengthening rib 60 to provide rigidity and ensure the cross-sectionalarea of the vent passage 32 is not reduced due to external pressure, asmay be caused by the patient rolling over onto their face during sleep.The detachable cap portion 36 also makes disassembly for cleaning easierand allows cap portions of various sizes to be used with a single bodyportion 34, thereby allowing the size and shape of the vent passage tobe easily and quickly varied for particular treatment applications.

Although the connector 10 has been described with reference to theswivel joiner 38 being interposed between the connector 10 and thebreathable gas supply conduit 31, it will be appreciated that theconduit can be joined directly to the body portion 34 if the ability toswivel is not required or if a swivel is provided elsewhere in the gassupply circuit. In that case, it is, of course, desirable for theexternal diameter of the gas supply conduit 31 to be equal to theadjacent external diameter of the exterior surface of the body portion34.

A second embodiment of connector 80 in accordance with the first aspectof the invention is shown in FIG. 6. Like reference numerals to thoseused in describing the first embodiment are used to indicate likefeatures in the second embodiment.

The primary difference between the connector 10 and connector 80 is thatthe inlet ports 41 are omitted and an inlet port 82 of the gas washoutvent passage 32 is incorporated into the mask end 28 of the connector80. Thus providing direct fluid communication between the interior ofthe mask 12 and the vent passage 32 and further minimizing CO₂retention. The inlet portion 50 of the vent passage 32 also provides arelatively long distance over which a gradual reduction in pressure canbe achieved. Further, the interior surface of the vent passage outlet 40forms a smooth prolongation with the adjacent exterior surface 46 of theswivel joiner 38 rather than the body portion 34, as with the firstembodiment.

FIG. 7 shows a third embodiment of the connector 90 according to thefirst aspect of the invention. Like reference numerals to those used indescribing the first embodiment will again be used to indicate likefeatures in the third embodiment. The connector 90 also has the ventpassage 32 in direct fluid communication with the interior of the mask12. However, in this embodiment, an inlet port 92 is formed in the maskshell 15.

FIG. 9 shows a fourth embodiment of the connector 130 according to thefirst aspect of the invention. Like reference numerals to those used indescribing the first embodiment will again be used to indicate likefeatures in the fourth embodiment. The connector 130 also has an inletport 132 formed in the mask shell 15, similar to the third embodiment.However, in this embodiment, both the interior surface 42 and thesmoothly prolongating adjacent exterior surface 46 are provided on theswivel joiner 38. As the gas vents to the atmosphere downstream of thejoin 134 between the swivel joiner 38 and the body portion 34, then anygas leaking through the join 134 cannot disturb the flow of gas at, orafter, the outlet 40. In this way, a further opportunity for turbulence,and thus noise generation, is eliminated.

FIG. 8 shows a first embodiment of a nasal respiratory mask 100 inaccordance with the second aspect of the invention. The mask 100includes a mask shell 102 and a mask cushion 104. The mask shell 102includes a mask inlet 106 for connecting in fluid communication with theoutlet of the breathable gas supply conduit 108. The mask 100 includes agas washout vent passage indicated generally by the reference numeral110.

The mask shell 102 is comprised of a body portion 112 and adetachable/attachable cap portion 114. The vent passage 110 includes aninlet port 116 formed in the body portion 112 of the mask shell 102. Theinlet port 116 is in direct fluid communication with the interior of themask 100. The vent passage 110 also includes an outlet 118 in fluidcommunication with the atmosphere. The outlet 118 includes an interiorsurface 120 on the exterior of the body portion 112 that forms a smoothprolongation with an adjacent surface 122 also provided on the exteriorof the body portion 112. The outlet 118 is adapted to direct the washoutgas in a direction substantially parallel to the longitudinal axis ofthe mask inlet 106 and away from the mask inlet 106.

As with earlier embodiments, the noise produced by venting the exhaledgas to the atmosphere is minimized by directing the vented gas on asmooth continuing surface before and after the outlet 118 and away fromthe mask 100, the patient and other potential disturbances.Additionally, as with the earlier connector embodiments, the cap portion114 is detachable from the body portion 112 for cleaning and orreplacement with a cap portion of same, or different, size or shape. Thevent passage 110 also similarly comprises an inlet portion 124 ofrelatively large cross-sectional area, a relatively long outlet portion126 of relatively small cross-sectional area and a transition portion128 of smoothly reducing cross-section extending from the inlet portion124 to the outlet portion 126.

Although the invention has been described with reference to thepreferred embodiments, it will be appreciated by those skilled in theart that the invention may be embodied in many other forms.

1-33. (canceled)
 34. A respiratory mask assembly for deliveringbreathable gas to a patient, comprising: a frame having a front surfaceand a rear surface adapted in use to face the patient, the frameincluding a main body providing an aperture therethrough for theintroduction of breathable gas into a nasal breathing cavity; and anelbow assembly swivelably coupled to the front surface of the frame, theelbow assembly including a swivel elbow that defines an intake port andan exhaust port separated from the intake port using a baffle, whereinthe elbow assembly includes an end portion that interfaces with theaperture of the frame.
 35. A respiratory mask assembly according toclaim 34, wherein the elbow assembly has a surface that is adapted todirectly engage a surface of a gas delivery tube.
 36. A respiratory maskassembly according to claim 34, wherein the elbow assembly includes aswivel connector between the elbow assembly and a gas delivery tube. 37.A respiratory mask assembly according to claim 34, wherein the elbowassembly includes a mating portion that is inserted into the apertureprovided in the frame and a lock is attached to the mating portion froman inner side of the frame so as to prevent withdrawal of the matingportion from the aperture.
 38. A respiratory mask assembly according toclaim 34, wherein the baffle is configured to direct exhaust gas awayfrom the nasal breathing cavity in a first direction that issubstantially opposite to a second direction in which the intake portdelivers incoming gas to the nasal breathing cavity.
 39. A respiratorymask assembly according to claim 34, wherein the elbow assembly includesa swivel elbow having a first end portion in communication with a gasdelivery tube and a second end portion detachably coupled to the frame.40. A respiratory mask assembly according to claim 39, wherein thesecond end portion of the swivel elbow includes a mating portion adaptedto engage the aperture of the frame, and wherein a lock is adapted toengage a receiving space in the mating portion when the second endportion reaches an operative position and thereby detachably couple theelbow assembly to the frame.
 41. A respiratory mask assembly accordingto claim 40, wherein the frame includes a flange surrounding theaperture, and the mating portion extends beyond the flange when thesecond end portion reaches an operative position to facilitate alignmentof the second end portion of the swivel elbow with respect to the frame.42. A respiratory mask assembly according to claim 34, furthercomprising a removable vent cover detachably connected to the elbowassembly, wherein the vent cover includes a main body and at least onevent aperture for gas washout.
 43. A respiratory mask assembly accordingto claim 34, further comprising a cushion provided to the frame.
 44. Anelbow assembly for a respiratory mask assembly that delivers breathablegas to a patient, the elbow assembly comprising: a swivel elbowincluding a first end portion in communication with a gas delivery tubeand a second end portion detachably and swivelably coupled to a frame,the swivel elbow defining an intake port and an exhaust port separatedfrom the intake port using a baffle, the baffle being configured todirect exhaust gas away from a nasal breathing cavity defined by theframe in a first direction that is substantially opposite to a seconddirection in which the intake port delivers incoming gas to the nasalbreathing cavity.
 45. An elbow assembly according to claim 44, furthercomprising a swivel connector between the swivel elbow and the gasdelivery tube.
 46. An elbow assembly according to claim 44, wherein theswivel elbow includes a mating portion that is inserted into an apertureprovided in the frame and a lock is attached to the mating portion froman inner side of the frame so as to prevent withdrawal of the matingportion from the aperture.
 47. An elbow assembly according to claim 44,wherein the second end portion of the swivel elbow includes a matingportion adapted to engage the aperture of the frame, and wherein a lockis adapted to engage a receiving space in the mating portion when thesecond end portion reaches an operative position and thereby detachablycouple the elbow assembly to the frame.
 48. An elbow assembly accordingto claim 44, further comprising a removable vent cover detachablyconnected to the swivel elbow, wherein the vent cover includes a mainbody and at least one vent aperture for gas washout.
 49. A respiratorymask assembly for delivering breathable gas to a patient, comprising: aframe having a front surface and a rear surface, opposite the frontsurface, and adapted in use to face the patient, the frame including anaperture provided through a main body thereof for the introduction ofbreathable gas to the patient; a cushion attachable to the frame; and aswivel elbow detachably coupled to the frame via a release mechanismpositioned on the swivel elbow, wherein the patient can breath throughthe aperture when the swivel elbow is detached from the frame.
 50. Arespiratory mask assembly according to claim 49, wherein the aperturehas a generally circular shape.